1. Field
Embodiments of the present invention relate to an apparatus and a method for automatically controlling a gain, and more particularly, to an apparatus and a method for automatically controlling a gain between acoustic input signals using phase information.
2. Description of the Related Art
With the popularization of mobile convergence terminals such as high-precision hearing aids of advanced medical devices, mobile phones, ultra mobile personal computers (UMPC), camcorders and the like, the need for application products using a microphone array are increasing. Most studies using the microphone array use a noise cancellation scheme based on a beamforming algorithm. Studies using microphone arrays have been conducted to find methods of improving voice call and recoding quality through the cancellation of directional noises, for use within a remote video conferencing system to automatically detect a speaker's location, and for use within robot technology to detect a target sound.
However, most beamforming algorithms may cause critical performance deterioration due to a gain difference between sensors. Specifically, in a Generalized Sidelobe Canceller (GSC) of a representative adaptive beamforming algorithm, target sound components are included in blocking signals due to a gain difference between signals, resulting in the occurrence of a phenomenon where a target sound is leaked into a resulting signal of an adaptive filter. Also, in the GSC, a shape of a beam is distorted due to a gain difference between microphones even when forming a basic beam so that a beam is not properly formed.
Generally, a gain difference between microphones occurs from characteristics of the microphones resulting from a fabrication defect or deterioration due to use over time. Methods for fabricating a microphone having fewer defects may solve the gain difference problem, however, the methods may not be optimal in view of reducing costs. Accordingly, a new algorithm which is less sensitive to the characteristics of microphones when using a microphone array of a lower price is required.